Electron discharge device circuit arrangements



May 10, 1960 Q v, TYLER 2,936,420

ELECTRON DISCHARGE DE VICE CIRCUIT ARRANGEMENTS Filed Feb. 23, 1956 2 Sheets-Sheet 1 lNvEN'r oe dww BY: MM #108,

AT'roRNaY May 10, 1960 v.41. TYLE 2 ELECTRON DISCHARGE DEVICE CIRCUIT ARRANGEMENTS Filed Feb. 23, 1956 2 Sheets-Sheet 2 W3! fik INVENTOE "mm W Bv fiww ATTORNEYS ELECTRON DISCHARGE DEVICE CIRCUIT ARRANGEMENTS Victor Joseph Tyler, Kelvedon, England, assignor to Marconis Wireless Telegraph Company Limited, London, England, a British company .This invention relates to electron discharge device cirrciiit arrangements and has for its object to provide improved valve circuit arrangements in which the maximum :amount of power which can be converted from DC. to A.C. by a valve of given design shall be large, and 1B. which the efficiency of such conversion shall be high as jcompared with the corresponding maximum power, and elficiency at maximum power, obtained with known comparable arrangements.

, It,is known in amplifiers and other valve circuit ar- 'rangernents to apply a rectangular or more or less rectangular voltage wave to the grid of a valve and to coni United States Patent better still, the second and fourth.

nect harmonic frequency circuits, in addition to the usual t fundamental frequency tank circuit, in the anode circuit of said valve. In general, however, such arrangements have been designed and arranged either to damp out harmonic frequencies from the anode circuitin such cases damping resistances have been connected across the harmonic frequency tuned circuits-or have consisted The proved efficiency of D.C.-A.C. power conversion as compared to these and other known arrangements.

According to this invention in its broadest aspect a discharge tube amplifier having a grid controlled discharge tube, means for applying a predetermined wave form of predetermined fundamental frequency as input to said tube and bias means for cutting off said tube during a predetermined fraction of each cycle of said input wave, includes in the output circuit of said tube, resonant means providing output at said fundamental frequency and addition-a1 resonant means resonant at at least one harmonic of said fundamental frequency so chosen that, when said input wave and bias are applied, the harmonics in the voltage and in the current wave forms at the output electrode of said tube are different.

The voltage wave form on the anode of the tube includes periodically recurrent substantially fiat valleys extending at least over the periods of occurrence of the peaks in the input voltage wave and comprises at least one harmonic of said fundamental frequency, while the wave form of current through the anode circuit is substantially rectangular and comprises harmonics other than those in the anode voltage waveform, said additional resonant network being resonant at and presenting high impedance to the harmonic or harmonics in said anode voltage wave form.

It is considered that, practically speaking, the two most important forms of embodiment of the present invention are those in which the valve is conductive for substantially 180 of each cycle of the input voltage wave form, and those'in which the valve is conductive for substantially 120 of each cycle. 7

In the former case the additional resonant network in series with the tank circuit will consist of a circuit reso- ;.nant to at least the second harmonic of the fundamental frequency, i.e. to twice the fundamental frequency, though it is preferred to provide resonances at twice and at four times the fundamental frequency. In such an embodiment the current wave form in the anode circuit will include odd harmonics only, and it is to be observed that, in accordance with this invention, in this case the additional resonant network is designed to be resonant at even harmonics onlyas stated the second harmonic, or

In the type of embodiment in which the valve is conductive for of each cycle, the additional resonant network may consist simply of a circuit tuned to three times the fundamental frequency, since the next lowest harmonic (above the third) which is absent from the current wave form is the sixth and the additional increase of efiiciency which would be obtained by making the additional resonant network resonant at the sixth harmonic also would be quite small. The invention is in sharp contra-distinction to those numerous Well-known amplifiers and other valve circuit arrangements in which a rectangular or more or less rectangular voltage wave is applied to the grid of a valve, and in which harmonic frequency circuits, in addition to the usual fundamental frequency tank circuit, are connected to the anode circuit of said valve either for the purpose of damping out harmonic frequencies from the anode circuit (in such cases damping resistances have been connected across the harmonic frequency tuned circuits) or for preventing the contribution to the output of harmonic frequency energy at harmonics present in the anode current wave farm for in these known arrangements the essential feature of the present inventionnamely the ensuring that the harmonics in the anode cur- .rent wave form are different from those in the anode voltage wave formis absent and little if any improvement in efficiency of D.C.A.C. power conversion is obtamed-certainly non-comparable to that obtained by this invention. The additional resonant networks provided in carrying out this invention are not damping devices but present high impedance at a harmonic or harmonics other than those in the anode current wave. There is thus no similarity with those known arrangements in which the anode circuit includes damping resistances connected across harmonically resonant circuits which are thus more damping devices, and to those other known arrangements in which the harmonic frequency circuits provided in the anode circuit would be resonant at odd harmonic frequencies where the present invention calls for circuits resonant at even harmonic frequencies and vice versa.

The invention is illustrated in and further explained in connection with the accompanying diagrammatic and graphical drawings in which Fig. 1 shows one embodiment diagrammatically; Figs. 2 to 5 inclusive show wave forms which occur in the arrangement of Fig. 1; Fig. 6 shows a second embodiment diagrammatically, and Figs. 7 to 10 inclusive show wave forms related to Fig. 6 in the same Way as the wave forms of Figs. 2 to 5 are related to the circuit of Fig. 1.

Referring to Fig. 1, this shows an arrangement in which the input voltage wave form is such as to open the valve for one half of each cycle. This voltage wave form, which is applied at the input terminals 1, is represented conventionally by the rectangular wave GV of Fig. 2. It is applied, as shown through the condenser 2 to the control grid of a valve 3 shown as a triode and which is biassed through a resistance -4 by a potential source 5 to cut off as represented by the broken line CU of Fig. 2. Since the valve cuts off at CU it will be obvious that the shape of the applied input wave form below theline CU is of no importance and may be anything.

In the anode circuit of the valve 3 is the usual flmdamental frequency tuned tank circuit 6, from across which output is taken at terminals 7. In series with this tank circuit is an additional resonant network 8 which might consist simply of a circuit tuned to twice the fundamental frequency, but preferably consists, as shown, of two parallel tuned "circuits marked 2F and 4F and resonant respectively at twice and four times the fundamental frequency.

With this arrangement the anode voltage wave form will besubstantially as shown by the curve AV of Fig. 3 with substantially flat valleys V substantially correspondingin time with thesubstantially flat peaks P which occur in the input volt-age wave form CV. The anode current wave form is shown at AC -in Fig. 4, while the practically sinusoidal output wave form at terminals 7 is shown at CV in Fig. 5. As will be seen, the anode 'current wave fornr AC includes odd harmonics only, while the anode voltage wave form includes even hari-fnonics, these being the harmonics to which the network '8 is resonant. o

The modification shown in Fig. 6 is one in which the input voltage wave form is such as to open the valve for one third of each cycle, and cut it oif for the other two thirds. In the set of Figs. 6 to the same references are used -for the same parts and curves as are employed in the set of Figs. '1 to 5, so that the former set of Figs. ,6 to 1'0 are practically self explanatory in view of the description already given of Figs. 1 to 5. As will be seen, the diiferences between Figs. 1 and 6 is that in the latter figure the additional resonant network is resonant :at three times the fundamental frequency, and the said network consists therefore of the single parallel tuned circuit marked 3F. ;I n the arrangement of Fig. 6 the anode current wave :AC of Fig. 9 includes all harmonics other than multiples of the third and the anode voltage wave -AV of Fig. 8 contains only the third harmonic.

-I claim: o

1. A discharge tube amplifier circuit having a grid controlled discharge tube including a cathode, grid and .an anode, an input circuit connecting said grid and cathode, -a second circuit connecting said anode and cathode and including a first parallel resonant circuit connected to said anode, and a second parallel resonant circuit serially connected between said first resonant circuit and said cathode, means for applying an input signal to said input circuit, said signal comprising a train of cyclic pulses each having a predetermined duration, said second resonant circuit being tuned to the fundamental frequency of said input signal, bias means for cutting "ofi "sa'id'tiilfe until each of said pulses exceeds a predetermined magnitude, the ratio of the duration of that part of each pulse in excess of said predetermined magnitude to the duration of one complete cy'cl'e being equal to the reciprocal of the order of "the harmonic to which sai'djfirst resonant circuit is tuned, and means for difiiling an output signal from said second resonantcircuit whereby the harmonics in the anouevoltage wave form ar rdifferentfror'n the harrnonicsin the anode current wave fonn V 2. A circuit according to claim 1 wherein "said means for applying an input 'sig'nal is means for applying a square wave input signal. o I r 3. A circuit according to claim 2 'wherein's'aid fire-ans for deriving an out-put "signal includes a pair of output terminals connected to opposite ends of said second resonant circuit. I

'4. -A circuit according to claim 2 wherein said first resonant circuit is tuned to the second harmonic'o'fsaid input "signal and wherein said bias means includes means for cutting off said tube for substantially of each pulse. g o p 5. A circuit according 'to claim 4 further including la "third resonant circuit resonant to the fourth harmonic of said input signal and serially connected between said second resonant circuit and said-anode.

-6. A circuit according to claim 2 wherein "said 'first resonant circuit is tuned to the third harmonic of said inputsignal and wherein said bias means includes means for biasing said grid to cut off for 240 of said 'pill'sis.

References Cited in the 'file of this jpa't'ent UNITED STATES PATENTS 2,416,424 Wilson Feb. 2 s, 1947 2,454,415 Tourshou Nov. 23, 194'8 2,559,144 Barack'et July 3, 1951 2,574,229 Schlesinger Nov. 6, 19:51 2,579,217 Tyzzer Dec. 18, 1951 2,582,271 Page -a Jan. 1 5, 1 952 2,642,525 Horn 'et a1. June 16, 1953 FOREIGN PATENTS 147:,43'5 Great Britain Mar. 22, T922 

